Rock drill



July 28, 1936. E'. F. TERRY y 2,048,958`v 1100K DRILL Filed May 29, 19:55

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` H125' ATTORNEY Patented July 28, 1936 i- Unirse stares wisest ROCK DRILL Edward F. Terry, Phillipsburg,` N.AJ., assignor to Ingersoll-Rand Company, Jersey City, N. J., a corporation of New Jerrsey Application Mayv 29, 1935, serial'No. casier 3 Claims. (C11. V121431)A This invention relates to rock drills of thereciprocatory piston type, and more particularly to the piston assembly for rock drills equipped with rifle bar rotation mechanism for effecting 5 rotation of the working implement which the piston actuates.

One object of the invention is to minimize `the weight of the piston.

Another object is to equip the piston with a composite rifle nut of which the component parts are so constructed and arranged with respect to each other as to preclude accidental loosening or withdrawal of the rifle nut from the piston.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawing accompanying this specification and in which similar reference characters refer to similar parts,

Figure l is a sectional elevation of so much of a rock drill as will serve to illustrate the invention and a practical application thereof, and

Figure 2 is a transverse view taken through Figure l on the line 2 2.

Referring more particularly to the drawing, designates a rock drill comprising a cylinder 2| and a back head 22 which may be secured to the cylinder 2| in any suitable manner.

The cylinder 20 is bored to provide a piston chamber 23 for the accommodation of a recipro- 3 catory hammer piston 24. The piston 24 is of the differential type having a head 25 which controls an exhaust port 26 intermediate the ends of the piston chamber, and a stem 21 on the piston extends slidably through a front cylinder washer 28 in the end of the cylinder.

The stem 27 is provided with the usual flutes 29 which slidably interlock with a suitable chuck device (not shown) whereby a wo-rking implement (not shown) may be guided and interlocked in a manner well understood to enable the rotary movement of the piston to be transmitted to the working implement for shifting it between blows of the piston 24.

In the rearward end of the cylinder 2| is an enlarged bore 36 to accommodate valve mechanism 3| and rotation mechanism 32. The valve mechanism 3|, of which only the chest 33 is shown, lies adjacent the rear end of the piston chamber 23 to serve as a closure for the piston chamber. Interiorly, the valve chest 33 may be formed to accommodate any suitable valve (not shown) for distributing the pressure fluid to the ends of the piston chamber 23, a front inlet passage 34 being shown extending through the cylinder from the valve mechanism 3| for this purpose. c

,.'The rotation mechanism 32, which is illus- Vtrated as being of a well known type, comprises .a rifle bar 35, that extends through the valve 5 mechanism 3| and interlockingly engages a rifle nut 36 disposed in a recess 3l in the head 25. A` head `38 on the rifle bar carries the usual spring-pressed pawls 39 adapted to engage teeth A40 ofa ratchet ring 4| for determining the direction'of rotation of the lriiie bar 35 and thus Qihepiston 12,4 Vand the devices connecting the piston with the Working implement.

The rifle nut 36, constructed in accordance with the practice of the. invention and which may be constructed of bronze, is internally fluted as is customary for engagement with the rilie bar 35. In length it preferably equals the depth of the recess 3l so that when occupying its assembled position in the piston the innermost end surface 42 of the rifle nut seats upon the bottom 43 of the recess 31 and the outermost end of the rifle nut 36 will then lie flush with the rear end of the piston 24. The wall of the rifle nut 36 is of only sucient thickness to enable the rifle nut to withstand the thrust imparted thereto by the rie bar at the instant of reversal of the piston 24, and the diameter of the nut is very considerably smaller than the diameter of the recess 3'| to permit the interposal of a sleeve 44 between the nut 36 and the skirt or wall of the piston head-25.

On the periphery of the nut 36 are threads 45 for engagement with corresponding threads 46 in the sleeve 44. The nut 36 is threaded into the sleeve 44 through the innermost end of the sleeve and has a head 41 which is provided with a bevelled surface 48 to frictionally engage a bevelled surface 49 in the sleeve 44. Thus, when the nut 46 is threaded tightly into the sleeve 44 the bevelled surfaces 48 and 49 may be drawn into tight frictional engagement with each other to assist in holding these elements against separation.

The sleeve 44 is preferably constructed of aluminum, a phenol formaldehyde condensation product or other material possessing the quality of low specific gravity as compared With the material of which the rifle nut 36 and the piston 24 are constructed. On the periphery of the sleeve 44 are threads 50 to engage the threads 5| in the 50 recess 31 for securing the sleeve 44 to the piston 24. The threads 45 and 5U on the rifle nut 36 and sleeve 44, respectively, are of opposite hand so that a thrust of the rie bar imparted to the rifle nut 36 tending to draw the bevelled surfaces 55 the thrusts resulting from the movement of 110,-. tation will cause the sleeve 44 to be pressed tightly against the shoulder of the nut 36 and tljieA end 42 of the nut to be pressed tightly against-the bottom surface 43 of the recess 3,1.

In practice, the present invention has been found to be highly desirable as a means for minimizing the weight of the pistonassembly without requiring the use of a piston head 25 of such dimensions as to reduce the pressure areas of the piston to impractical sizes. By employing an aluminum sleeve as a medium for binding the rifle nut 36 to the piston the end areas of the piston may be held to known practical dimensions and at the same time the weight of the piston assembly will be considerably decreased. In the oase of an aluminum sleeve 44 or one constructed oi' a product of phenol formaldehyde condensation the weight ofthe sleeve will be approximately only one-third of the material which it displaces. Thus are obtained the desirable qualities of durability and lightness of weight of the nut to the piston.

,the sleeve and seating upon the bottom of the "recess, and a beveled surface on the rie nut frictionally engaging the seating surface to prevent withdrawal of the rifle nut from the sleeve.

2. In arock drill, the combination of a piston having a threaded recess and a rie bar extending into the recess, a sleeve having external threads to engage the threads of the recess and having internal threads of opposite hand to the external threads, a rie nut threaded into the sleeve, and cooperating portions on the sleeve and the rifle nut to prevent withdrawal of the rifle nut from the sleeve. Y

3` Apiston assembly for rock drills having rie bar rotation mechanism, comprising a piston hav- 2 ing a threaded recess, a rifle nut in the recess having external threads of opposite hand to the threads of the recess, and an aluminum sleeve .threaded into the recess and being threadedly connected to the rifle nut for securing the rifle EDWARD F. TERRY. 

